1. Field of the Invention
The invention relates to a resist pattern-forming method, a resist-pattern-forming radiation-sensitive resin composition, and a resist film.
2. Discussion of the Background
In the field of microfabrication such as production of integrated circuit devices, a fine resist pattern is formed by forming a resist film on a substrate using a resin composition that includes an acid-labile group-containing polymer, exposing the resist film by applying short-wavelength radiation (e.g., excimer laser light) to the resist film via a mask pattern, and removing the exposed area using an alkaline developer.
In recent years, liquid immersion lithography has been extensively used as a method for forming a fine resist pattern having a line width of about 45 nm. Liquid immersion lithography has an advantage in that the depth of focus decreases to only a small extent, and high resolution can be obtained even when the numerical aperture (NA) of the lens is increased. A resin composition used for liquid immersion lithography is required to prevent a decrease in film performance and contamination of the lens or the like by suppressing elution of an acid generator and the like from the resist film into the immersion medium, and make it possible to implement high-speed scan exposure by preventing a situation in which watermarks remain through an improvement in draining capability of the surface of the resist film.
Japanese Patent Application Publication (KOKAI) No. 2005-352384 discloses a technique that forms an upper layer film (protective film) on the resist film in order to deal with such a demand. However, this technique takes time since it is necessary to separately form the upper layer film. Therefore, a method that improves the hydrophobicity of the surface of the resist film has been studied. WO2007/116664 discloses a resist pattern-forming method that utilizes a resin composition that contains a fluorine-containing polymer that exhibits high hydrophobicity.